Feeding apparatus for pulverized fuel



April 27,1926. 1,582,446

H. D. BOWMAN FEEDING APPARATUS FOR PULVERIZED FUEL Filed Dec. 22. 1922ZSheets-Sheet 1 l I l l INVENTOR April 27 1926.

v H. D. BOWMAN FEEDING APPARATUS FOR PULVERIZED FUEL Filed Dec. .22.1922 2 Sheets-Sheet J manning} Patented Apr. 27, 1926.

UNITED STATES g I 1,582,446 PATENT OFFICE.

HARRY D. BOWMAN, 015 EAST ORANGE, NEW JERSEY, ASSIGNOR OE ONE-HALF TOEUGENE VfMYERS, OF EAST ORANGE, NEW JERSEY.

FEEDING APPARATUS FOR PULVERIZED FUEL,

Application filed December 22, 1922; Serial No. 608,437.

To all whom it may concern:

Be it known that I, HARRY D. BOWMAN, a citizen of the United States ofAmerica, residing in East Orange, in the county of Essex and State ofNew Jersey, have invented certain new and useful Improvements in FeedingApparatus for 'Pulverized Fuel,

of which the following is a specification Pulverized fuel has recentlycome into somewhat extended use, particularly in connection with steamboilers, the fuel being fed mechanically into the fire-box and thecombustion taking place largely while the fuel is in suspension in theair within the fire zone. The method usually adopted for feeding thefuel consists in mechanically transferring the fuel to a point more orless adjacent to the fire-box, and blowing it into the latter by acurrent of air,-the air serving as a carrier for the fuel and alsoproviding 7 the necessary oxygen to support combustion.

Difficulties have sometimes been encountered in the operation of suchdevices due to the fact that for one reason or another there has been apartial or total failure of the air'supply with the result that the fuelhas accumu ated within the air pipe, and has become so-consolidated orpacked that itis difficult to remove it, oftentimes necessitating ashutting down of the boiler for considerable periods of time. Diflicultyhas also been encountered in proportioning the speed of feed of the fuelto the requirements of the furnace, with the result that there has beenan' excess or a scarcity of fuel as compared with the steamingrequirements, so that irregular or wasteful results have been obtained.

According to the present invention I provide means for automaticallycontrolling the feed of the fuel in relation to the pressure of airWithin the feed pipe, so that in case of reduction of air current, thefeed is either stopped or lessened before the danger point is reached.Furthermore, in the preferred form of the invention, I provide a meanswhereby the fuel feed cannot be started until the air current hasreached the proper proportions. My invention also provides an improvedfuel feeder by which the feed is determined with great accuracyso thatunder given conditions the feed will be uniform to a high degree. Theinvention also comprises certain other improvements which will behereinafter more fully described.

Referring to the drawings, which illustrate one form of the invention,

Figure 1 is a side view,- partly in elevation, and partly inlongitudinal vertical section.

Fig. 2 is a section on the line 2-2 in Fig. 1.

Referring to the drawings, I will first de-' scribe the preferred formof the device for feeding the fuel in measured quantities. In

this construction A is a hopper or connecting pipe of suitabledimensions, adapted to be connected with a fuel bin orother source ofsupply. The hopper leads to a primary feed chamber B, which preferablyis circular in form, and within the primary feed chamber B is rotated acylindrical feed member 0 which has on its periphery a series of pocketsof an approved form, those shown being circu ar. The feed cylinder C isbest mounted on a shaft E which has bearings F and G in the housingof'the machine. The ends of the feed cylinder prefer ably comprisecircular plates, such as H H, a convenient construction being to castthe cylinder in one piece. Below the feed chamber is a passage I,preferably running the full length of'the cylinder and beingapproximately as wide as the pockets D. The

1 result of thisconstruction is that as the feed cylinder is rotated,each of the pockets receives a measured supply of fuel when in itsuppermost position, and carries it around until the fuel is droppedthrough the passage I. This construction prevents any arching of thefuel above the feed cylinder, and operates very efficiently with fuelswhicl are'very difficult to handle, such as Wet 0 even partly frozencoal. It also is capable o1 handling effectively fuels in which becauseof their fineness and moisture there is a strong tendency for theparticles to adhere. It will be understood that as a pocket is filledfrom the hopper, the excess is wiped off by the hopper wall as the feedcylinder rotates.

The opening I leads to a circular trough J in which rotates a feed screwK, the flights of which preferablyrun very close to the bottom andsidewalls of the trough and nearly meet the edges of the feed c'ylinderbetween the pockets. At the exit end of the trough, and immediatelyadjacent the I end of the screw Imay arrange a grid com-- constructionwhich will place a slight backpressure on the fuel and cause the mass tobe divided up before it reaches the air pipe L.

In the construction shown I have illustrated the feeding device asdriven by an electric motor M. As illustrated, the motor shaft N iscoupled to a variable speed mechanism 0, the driven shaft of which 0carries a pinion O which drives the shaft 0 of the screw. A pinion O isalso mounted on the screw shaft and turns a gear 0 keyed to the cylindershaft E. This gearing suitably reduces the speed of the motor shaft, andstill further reduces the speed of the feed cylinder.

I referably use some form of a variable speed gearing O of well-knowntype so as to produce a capacity for at least some variation in relativespeeds of the motor and feed mechanism. In the construction shown, whichis of a common type, the motor shaft drives a friction gear P, while anopposite gear Q is keyed on the feed cylinder shaft. Between the twogears P and Q, are arranged transmission gears R which run 111 grooves Sand T formed in the gears P and Q. By tilting the transmission gears oneway or the other, the relative speed of the gear Q relative to gear P iseither increased or reduced within limits of twenty or thirty per cent,which is ordinarily suflicient for the purpose. It will be understoodthat the variable speed mechanism is intended for fine adjustments, andthat if adjustments of greater magnitude are required, any of theordinary variable speed mechanisms may be employed, or if desired, themotor may be provided with a rheostat or other suitable speed control.

ll hen the motor is operated, the feed cylinder conveys to the screwcertain measured quantities of fuel, which the screw in turn feedsforward into the air pipe L. Assuming a constant flow of air through thefeed pipe L which leads to the fire-box which is proportioned to thespeed of feed, or vice versa, it is evident that very uniform andregular quantities of fuel in practically a continuous stream will befed to the furnace.

I equently happens, however, that because breakdown of the air system,caused by failure of the compressor or for other reasons, that thecurrent of air eitherfails entirely, or is insufficient to move theamount of fuel which is being fed. Unless this is very quicklydiscovered, and the fuel feed stopped, the air pipe will fill up withfuel and become clogged, frequently to such extent that it requiresconsiderable time to remove the fuel and a shut-down of greater or lessduration is the result.

According to my invention I provide means for controlling the feed ofthe fuel which governed by the air current. I

prefer, however, to use a pressure system which takes its pressure fromthe air pipe, and maintains a piston in its advanced position, thusholding the motor switch closed. In the drawing, wherein thisconstruction is shown, I utilize an air pipe V which leads to a cylinderIV conveniently formed in the motor base, in which moves a piston W,which piston operates one arm X of a switch lever, the other arm ofwhich Y is adapted to make contact with a terminal Z, thus closing thecircuit of the motor leads, one of which is shown diagrammatically at Aand the other of which is shown at B. the pressure in the pipe V isrelieved, the superior weight of the arm Y of the switch lever causes itto drop, thus breaking the circuit. Any other switching device may beemployed. Preferably a. pressure gauge C is introduced into the system,so that the pressures may be conveniently read.

Ihe construction thus described stops the entire apparatus when the airpressure in the pipe L falls below the predetermined working pressure.Furthermore, in the absence of a hand control, it is impossible tooperate the fuel feeder until the air in the pipe L has reached itsproper pressure in initially starting, or until it resumes its properpressure after an interruption.

It will be understood that various changes may be made in theconstruction shown without departing from the spirit of the invention.

What I claim is:

1. A fuel feeding apparatus having a fuel feeder, a conduit into whichthe fuel is fed, an air supply for conveying the fuel through saidconduit after it is fed, and means governed by the pressure of the airsupply within said conduit for stopping the feeder upon a decrease ofthe air supply.

2. A fuel feeding apparatus having a fuel feeder, a conduit into whichthe fuel is fed, an air supply for conveying the fuel through saidconduit after it is fed, :11 ans governed by the pressure of the airsupply within said conduit for stopping the feeder upon a decrease ofthe air supply, said means including a driving device for the feederoperated when the pressure of the air supply is normal, and means forstopping the operation of said driving device when. the pressure the airbecom s reduced.

3. A fuel feeding apparatus ha ing a fuel feeder, a conduit into whichthe fuel is fed, an air supply for conveying the fuel through saidconduit after it is fed, means governed by the pressure of the airsupply within said conduit for stopping the feeder upon a decrease ofthe air supply, said means including a driving device for the feederoperated when the pressure in the air supply is normal, piston actuatedby the rising and falling of pressures said conduit, and a start- -When1,ss2,44e

ing and stopping device for the feeder operated by said piston.

4. An apparatus for feeding fuel, comprising a hopper, a cylinderprovided with pockets arranged below said hopper, means for rotating thecylinder, a conveying device arranged to take the discharge of thecyliinder and feed-it forwardly, a conduit'into which said discharge isfed, an air supply for conveying the fuel thus fed along said conduit,and means governed by the pressure of the air supply within the conduitfor stopping said conveying device when the pressure of air within theconduit is reduced.

5. An apparatus for feeding fuel, compris-- ing a hopper, a cylinderprovided with pockets arranged below said hopper, means forrotating thecylinder, a conveying screw arranged to take the discharge of thecylinder and feed it forwardly, a motor for driving said cylinder andscrew, a conduit into which said discharge is fed, an air sup-. ply forconveying the fuel after it is fed, and means governed by the pressureof the air supply within the-conduit for stopping said motor when thepressure of air Within the conduit is reduced.

In witness whereof, I have hereunto signed my name.

HARRY D. BOWMAN.

